<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>伪类选择器</title>
<style>
       a:link{
       	color:red;
       }
      a:visted{
      	color:blue;
      }
      input:hover{
      	background-color: red;
      }
      input:focus{
      	background-color: blue;
      }
      button:active{
      	background-color: lightgreen;
      }
</style>
</head>
<body>

	<a href="#" >外部链接</a><br>
	<input type="text">
	<button type="button">提交</button>

</body>
</html>